250 



and with 2°o maltose 1 140 secs. As the enzyme of Aspergillus niger 

 changes starch into maltose (see page 251, note), the experiments 

 on glucose are not influenced by this factor at ail, but where the 

 culture solution also contains starch, the maltose, which is formed, 

 may act as an Inhlbitory influence during the first few days. This 

 can not be the mam cause however, because the minimum is only 

 reached some time after ail of the foodmaterials hâve been con- 

 sumed. 



The total amount of enzyme, produced at the end of the experi- 

 ment, is always the same, no matter what the concentration was of 

 the culture solution. In the séries on 0.5 — 2.5% at least, we see 

 that the same high maximum is reached in ail cases. The maximum 

 is not so high in the séries on 4°o, but in this case the inhibitory 

 substances are formed more abundantly and it will therefore take a 

 longer time before ail of the diastase has again been set free. The 

 same of course is true of the 5% solution. 



I therefore draw the conclusion, that neither qualitative nor quan- 

 titative changes in the foodmaterial hâve any influence at ail on the 

 amount of diastase which is produced by Aspergillus niger. This 

 must be true of culture solutions containing glucose and (or) starch 

 at least. A high concentration temporarily seems to change the 

 course of events. That is why I think that the curve in fig. 1 1, for 

 the third séries on starch 0.5%, is the only one, which gives a true 

 picture of the course, taken by the production of diastase of the 

 fungus (compare also fig. 2). 



Some important facts seem to support the view I hold on this 

 matter. 



Turning to fig. 1 3 and table 1 on the séries, grown on 5^o maltose 

 (1 1 — 13; 1040.5), we see that there is an apparent maximum, which 

 is followed by a decrease. This fall in concentration is however 

 not nearly as large as in the case of the 5^o glucose séries, and the 

 subséquent nse is not so great either. Evidently Aspergillus niger 

 produces very little maltase. If a culture solution, containing 

 maltose is used, the maltose takes a very long time to disappear. 

 Glucose and other foodmaterials had generally disappeared on the 



